Couldn't you just use something like:

eg:

A. Team 1 odds = 1.50
x
B. Team 2 odds = 1.85
x
C. Team 3 odds = 2.00
x
D. Team 4 odds = 1.45

E. Total odds = 8.0475

F. Win Total = 100.00

100 / 8.0475 = 12.426219

A x B x C x D = E

F / E = Bet amount to reach $100.00